Exemplary embodiments of the invention disclosed herein relate to a liquid crystal display (LCD) apparatus, and more particularly, to an LCD apparatus having a contact sensing function.
A liquid crystal display (LCD) apparatus is currently one of flat panel display apparatuses being most widely used and includes, two sheets of display plates on which field generating electrodes are formed such as a pixel electrode and a common electrode, and a liquid crystal layer in between. The LCD apparatus applies a voltage to the field generating electrode to generate an electric field for the liquid crystal layer, and this electric field determines the directions of liquid crystal molecules on the liquid crystal layer and controls the polarization of incident light to display an image.
A touch screen panel is a device that enables a user to execute an icon so that a machine such as a computer can perform a desired command or to write a text or draw a picture by contacting a finger or a touch pen/stylus with a screen.
An LCD apparatus including the touch screen panel may find out whether a user's finger or touch pen is in touch with the screen and information on a contact location. However, such an LCD apparatus has limitations in cost increase due to the touch screen panel, yield decrease due to an additional process of bonding the touch screen panel to a liquid crystal display plate, luminescence decrease of the liquid crystal display plate and increase in product thickness.
Thus, a technology that enables a display panel for displaying an image (instead of the touch screen panel) to include a light sensing pixel including a thin film transistor in addition to a pixel (a display or light emitting pixel) has been developed. The light sensing pixel may sense a change in pressure applied to a screen by a user's finger and/or a change in light to enable the LCD apparatus to find out whether the user's finger is in contact with the screen and information on a contact location. However, since the display panel includes the light sensing pixel, there is a limitation in that the aperture ratio of the display panel decreases.